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• Can't get the right formula to set frame pts for a stream using libav

  4 avril 2022, par user1365836

  I'm trying to save a stream of frames as mp4.
Source framerate is not fixed and it stay in the range [15,30]

  


  Encoder params :

  


  ...
eCodec.time_base = AVRational(1,3000);
eCodec.framerate = AVRational(30, 1);
...


  


  Stream params :

  


  eStream = avformat_new_stream(eFormat, null);                
eStream.codecpar = codecParams;
eStream.time_base = eCodec.time_base;


  


  Decoder time_base is 0/1 and it marks each frame with a pts like :

  


  480000
528000
576000
...


  


  PTS(f) is always == PTS(f-1)+48000

  


  Encoding (dFrame is the received frame, micro the elapsed time in microseconds) :

  


  av_frame_copy(eFrame, dFrame);
eFrame.pts = micro*3/1000;


  


  This make the video playing too fast.
I can't understand why, but changing micro*3/1000 to micro*3*4/1000 make the video play at the correct speed (checked against a clock after many minutes of varying fps)

  


  What am I missing ?

  


• ffmpeg timeout with rtsp

  17 janvier 2024, par eSlavko

  I have script that capture image from wifi camera with ffmpeg.
It works fine until camera is not reachable due to network troubles.
The script stuck in ffmpeg capture and never exit. Is it possible to have some kind of timeout ? -stimeout (in miliseconds) seems not working.

  


  There is part of script that capture images. (there are some manipulation after that)

  


  #!/bin/bash
week="$(date '+%Y_%U')"
ts="$(date '+%Y-%m-%d_%H:%M:%S')"
ffmpeg -rtsp_transport tcp -y -i "rtsp://192.168.64.101" -frames:v 1 $week/$ts.jpg -stimeout 3000 -y


  


  I did test on other camera and results are :

  


  ffmpeg -y -i "rtsp://192.168.64.112:8554/profile0" -frames:v 1 Ilatest.jpg


  


  Does work OK, but with timeout of 5 seconds as

  


  ffmpeg -timeout 5000000 -y -i "rtsp://192.168.64.112:8554/profile0" -frames:v 1 Ilatest.jpg


  


  doesn't and I got error report as :

  


  ffmpeg version 4.2.4-1ubuntu0.1 Copyright (c) 2000-2020 the FFmpeg developers built with gcc 9 (Ubuntu 9.3.0-10ubuntu2)
...
...
[rtsp @ 0x55d250488740] Unable to open RTSP for listening
rtsp://192.168.64.112:8554/profile0: Cannot assign requested address


  


• Multiple sounds + watermark overlay not working with ffmpeg

  9 avril 2022, par Dady

  I have a problem with an ffmpeg command.

  


  I want to add the same sound several times in the final video and then add a watermark above.

  


  When I do the full command, it doesn't work correctly because the sound is only played once (the first reference) :

  


  


  ffmpeg -i "assets/frame%05d.png" -i "assets/sound.mp3" -loop 1 -i
"assets/watermark.png" -filter_complex
"[1:a]adelay=1000|1000[s1] ;[1:a]adelay=3000|3000[s2] ;[s1][s2]amix=2[a] ;[0:v][2:v]overlay=shortest=1[outv]"
-map "[outv]" -map "[a]" -c:v libx264 -pix_fmt yuv420p -preset ultrafast -y "result.mp4"

  


  


  When I don't add the watermark, it works correctly :

  


  


  ffmpeg -i "assets/frame%05d.png" -i "assets/sound.mp3" -filter_complex
"[1:a]adelay=1000|1000[s1] ;[1:a]adelay=3000|3000[s2] ;[s1][s2]amix=2[a]"
-map 0:v -map "[a]" -c:v libx264 -pix_fmt yuv420p -preset ultrafast -y "result.mp4"